psychrophilic

You’ve probably noticed that stuff is really expensive these days. And one of the most expensive things is staying warm (as I type this I’m wearing two jumpers, a scarf and gloves, and I have an extra-long hot water bottle wrapped round me – still cold though). Thanks to soaring energy prices, we’ve all had to become psychrophilic.

As you’ve probably guessed, psychrophilic is a scientific term for organisms that love living in cold environments – think glaciers, deep-sea trenches and the like. They’re usually bacteria, fungi, microbes and other tiny little critters like that.

‘Psychrophilic’ first turned up as a scientific term in the early 20th century. It’s a combination of two Greek words – ‘psychros’ meaning ‘cold’ and ‘philos’ meaning ‘loving’. Sometimes etymology really isn’t rocket science.

The opposite of psychrophilic is, of course, thermophilic. These heat-loving organisms thrive in temperatures above 45°C. Psychrophilic and thermophilic organisms are often also extremophiles, another former word of the week.

Psychrophilic organisms are super helpful to science. Here are a couple of examples:

Antarctic krill in action – actual size, around 6cm

• colwellia psychrerythraea: a bacterium found in the deep sea, particularly in the Arctic and Antarctic. It produces proteins that stay active at really low temperatures, which is handy for things like food preservation

• pseudoalteromonas haloplanktis: this is another type of bacterium which also thrives in the Antarctic. It’s studied for its enzymes, which we use to clean clothes in cold water

• Antarctic krill: this tiny shrimp-like crustacean also lives in the freezing waters around Antarctica. It’s what’s known as a keystone species, which means it plays a critical role in maintaining the structure and balance of its ecosystem. Without this unassuming little creature, the Southern Ocean ecosystem would be completely devastated, as would the wider environment. The best things really do come in small packages. (Oh, and just to end on a positive note, you’ll be pleased to hear that Antarctic krill is one of the few species in the world that isn’t endangered. So the Southern Ocean ecosystem should be okay for now. Apart from all the climate change. Sorry.)

extremophile

It’s another ‘-phile’ word this week, but there’s nothing to worry about, honest. An extremophile is an organism that thrives in extreme environments previously thought to be uninhabitable, for example under massive pressure or really bastard cold. These organisms not only tolerate these conditions – for many, they need them to survive. Extremophiles have been found 6.7 km below the Earth’s surface, more than 10km deep in the ocean at pressures of up to 110 MPa (which is a lot, apparently), in acid, in frozen seawater at -20°C and in underwater hydrothermal vents at temperatures of 122°C. The name is made from the Latin extremus meaning, um, ‘extreme’, and the Greek philiā which means ‘love’.

A tardigrade*. Doesn’t he look like he’s about to start singing ‘Always look on the bright side of life’?

Extremophiles are also normally polyextremophiles (‘poly’ meaning ‘many’), which means they can live in more than one shit place – for example, the deep ocean is generally very cold and also under high pressure. So that’s a double whammy. And most extremophiles are microorganisms, but not all – the tardigrade (which I thought was a made-up thing in Star Trek) is one example. Also known as a water bear or moss piglet (awwww), a tardigrade is a microscopic eight-legged animal that thrives in environments that would kill most other forms of life – on mountaintops including the Himalayas, at the bottom of the sea, in mud volcanoes (which are literally what they sound like) and even in solid ice. They can go up to 30 years without food or water, and have been on earth for about 600 million years, which means they pre-date the dinosaurs by a mere 400 million years.

Not long ago, some nice scientists chucked a load of tardigrades out into outer space to see what would happen. Not only did lots of them survive, but some of them even went on to have babies. And in August 2019, scientists reported that some tardigrades might be living on the moon after an Israeli lunar lander carrying thousands of them crash landed (although it’s since been reported that they probably didn’t survive the impact, booooo). Both of these things sound like the start of really good sci-fi horror films.

The name ‘water bear’ comes from the way tardigrades walk, which apparently resembles the way bears get around. The largest ones can get to a (still pretty tiny) 1.5mm, which means you can see them using a bog-standard microscope if you have such a thing.

Extremophiles like the tardigrade are proof that life can exist in many different forms, and that oxygen and water aren’t pre-requisites. In the words of well-known mathematician and chaos theory specialist Dr Ian Malcolm (AKA Jeff Goldblum in Jurassic Park): ‘Life, uh, finds a way.’

*Wikipedia says I have to credit that tardigrade photo with this horrible bit of text: photo by Bob Goldstein and Vicky Madden, UNC Chapel Hill – http://tardigrades.bio.unc.edu/pictures/ >https://www.flickr.com/photos/waterbears/sets/72157607218607395/ >https://www.flickr.com/photos/waterbears/2851666759/in/album-72157607218607395 (note permission below), CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4747599).